Tissue sealing instrument with tissue-dissecting electrode

ABSTRACT

An electrosurgical instrument includes an elongated shaft extending distally from a housing and an actuating mechanism operably coupled to a proximal portion of the elongated shaft and configured to move the elongated shaft. First and second jaw members are coupled to a distal portion of the elongated shaft. The first jaw member is pivotable relative to the second jaw member between open and closed positions. An electrically conductive tissue sealing surface is disposed on each of the jaw members and is adapted to connect to a source of electrosurgical energy. A tissue-dissecting electrode is disposed on a distal end of at least one of the jaw members in spaced relation to the tissue sealing surface and is adapted to connect to a source of electrosurgical energy. An insulator couples the tissue-dissecting electrode to the jaw member and electrically insulates the tissue-dissecting electrode from the jaw member.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of and priority to U.S. Provisional Application Ser. No. 61/932,978, filed on Jan. 29, 2014, the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates generally to the field of surgical instruments. In particular, the disclosure relates to an endoscopic electrosurgical forceps capable of electrosurgically sealing tissue and electrosurgically dissecting tissue.

2. Background of Related Art

Instruments such as electrosurgical forceps are commonly used in open and endoscopic surgical procedures to coagulate, cauterize and seal tissue. Such forceps typically include a pair of jaw members that can be controlled by a surgeon to grasp targeted tissue, such as, e.g., a blood vessel. The jaw members may be approximated to apply a mechanical clamping force to the tissue, and are associated with at least one electrode to permit the delivery of electrosurgical energy to the tissue. The combination of the mechanical clamping force and the electrosurgical energy has been demonstrated to join adjacent layers of tissue captured between the jaw members. When the adjacent layers of tissue include the walls of a blood vessel, sealing the tissue may result in hemostasis, which may facilitate the transection of the sealed tissue. A detailed discussion of the use of an electrosurgical forceps may be found in U.S. Pat. No. 7,255,697 to Dycus et al.

A bipolar electrosurgical forceps typically includes opposed electrodes disposed on clamping faces of the jaw members. The electrodes are charged to opposite electrical potentials such that an electrosurgical current may be selectively transferred through tissue grasped between the electrodes. To effect a proper seal, particularly in relatively large vessels, two predominant mechanical parameters must be accurately controlled; the pressure applied to the vessel, and the gap distance established between the electrodes.

Both the pressure and gap distance influence the effectiveness of the resultant tissue seal. If an adequate gap distance is not maintained, there is a possibility that the opposed electrodes will contact one another, which may cause a short circuit and prevent energy from being transferred through the tissue. Also, if too low a force is applied the tissue may have a tendency to move before an adequate seal can be generated. The thickness of a typical effective tissue seal is optimally between about 0.001 and about 0.006 inches. Below this range, the seal may shred or tear and above this range the vessel walls may not be effectively joined. Closure pressures for sealing large tissue structures preferably fall within the range of about 3 kg/cm² to about 16 kg/cm².

SUMMARY

The present disclosure relates to an electrosurgical apparatus and methods for performing electrosurgical procedures. More particularly, the present disclosure relates to electrosurgically sealing and dissecting tissue.

The present disclosure describes an electrosurgical instrument for treating tissue. The electrosurgical instrument includes an elongated shaft extending distally from a housing and defining a longitudinal axis. The electrosurgical instrument also includes an actuating mechanism operably coupled to a proximal portion of the elongated shaft. The term “distal” refers herein to an end of the apparatus that is farther from an operator, and the term “proximal” refers herein to the end of the electrosurgical forceps that is closer to the operator. The actuating mechanism is moveable relative to the housing to move the elongated shaft along the longitudinal axis. An end effector is coupled to a distal portion of the elongated shaft. The end effector includes first and second jaw members. The first jaw member is pivotable relative to the second jaw member between an open position and a closed position. An electrically conductive tissue sealing surface is disposed on each of the jaw members and is adapted to connect to a source of electrosurgical energy. The tissue sealing surfaces are configured to conduct electrosurgical energy through grasped tissue. A tissue-dissecting electrode is disposed on a distal end of at least one of the jaw members in spaced relation to the tissue sealing surface. The at least one tissue-dissecting electrode is adapted to connect to a source of electrosurgical energy and is configured to electrosurgically dissect tissue. An insulator couples the at least one tissue-dissecting electrode to the jaw member and is configured to electrically insulate the at least one tissue-dissecting electrode from the jaw member.

Additionally or alternatively, the at least one tissue-dissecting electrode and at least one of the tissue sealing surfaces are configured to generate a bipolar energy potential therebetween for dissecting tissue.

Additionally or alternatively, the at least one tissue-dissecting electrode extends distally from a distal end of the at least one jaw member.

Additionally or alternatively, the at least one tissue-dissecting electrode is configured to dissect tissue when the first jaw member is in the open position.

Additionally or alternatively, the at least one tissue-dissecting electrode is configured to dissect tissue when the first jaw member is in the closed position.

Additionally or alternatively, at least one of the tissue sealing surfaces includes a flex circuit disposed thereon configured to electrically connect the at least one tissue-dissecting electrode to a source of electrosurgical energy.

Additionally or alternatively, the at least one tissue-dissecting electrode is configured to be energized with a first polarity of electrosurgical energy and at least one of the tissue sealing surfaces is configured to be energized with a second polarity of electrosurgical energy.

Additionally or alternatively, the at least one tissue-dissecting electrode is electrically deactivated during sealing of tissue grasped between the tissue sealing surfaces.

Additionally or alternatively, the end effector is configured to electrosurgically dissect tissue contacted by the tissue-dissecting electrode and at least one of the tissue sealing surfaces.

Additionally or alternatively, the electrosurgical instrument also includes a stationary actuation member axially disposed within the elongated shaft and a camming slot disposed on the second jaw member. The stationary actuation member includes a cam pin mechanically coupled to a distal end thereof and the camming slot is configured to engage the cam pin to move the first jaw member between the open position and the closed position upon movement of the elongated shaft along the longitudinal axis.

Additionally or alternatively, the electrosurgical instrument also includes a knife advanceable along the longitudinal axis through a knife channel extending at least partially through the jaw members to cut tissue grasped therebetween.

Additionally or alternatively, the electrosurgical instrument also includes a switch supported by the housing and engageable by the actuating mechanism to control delivery of electrosurgical energy from a source of electrosurgical energy to the end effector.

Additionally or alternatively, the second jaw member is mechanically coupled to a distal end of the elongated shaft and the first jaw member is moveable relative to the second jaw member.

Additionally or alternatively, the at least one tissue-dissecting electrode conducts a first polarity of electrosurgical energy and at least one of the tissue sealing surfaces conducts a second polarity of electrosurgical energy.

Additionally or alternatively, the tissue sealing surfaces are configured to electrosurgically cut tissue grasped therebetween.

According to another aspect of the present disclosure, an electrosurgical instrument is provided. The electrosurgical instrument includes an elongated shaft extending distally from a housing and defining a longitudinal axis. The electrosurgical instrument also includes an actuating mechanism operably coupled to a proximal portion of the elongated shaft. The actuating mechanism is moveable relative to the housing to move the elongated shaft along the longitudinal axis. An end effector is coupled to a distal portion of the elongated shaft. The end effector includes first and second jaw members. The first jaw member is pivotable relative to the second jaw member between an open position and a closed position. An electrically conductive tissue sealing surface is disposed on each of the jaw members and is adapted to connect to a source of electrosurgical energy. The tissue sealing surfaces are configured to conduct electrosurgical energy through grasped tissue. A tissue-dissecting electrode is disposed on a distal end of the second jaw member in spaced relation to the tissue sealing surface of the second jaw member. The tissue-dissecting electrode is adapted to connect to a source of electrosurgical energy and is configured to electrosurgically dissect tissue using a bipolar energy potential generated between the tissue-dissecting electrode and at least one of the tissue sealing surfaces. An insulator couples the tissue-dissecting electrode to the second jaw member and is configured to electrically insulate the tissue-dissecting electrode from the second jaw member.

Additionally or alternatively, the tissue-dissecting electrode is configured to conduct a first polarity of electrosurgical energy, one of the tissue sealing surfaces is configured to generate a second polarity of electrosurgical energy, and the other tissue sealing surface is configured to be electrically deactivated.

According to another aspect of the present disclosure, an electrosurgical system is provided. The electrosurgical system includes a source of electrosurgical energy and an electrosurgical instrument operably coupleable to the source of electrosurgical energy. The electrosurgical instrument includes an elongated shaft extending distally from a housing and defining a longitudinal axis. The electrosurgical instrument also includes an actuating mechanism operably coupled to a proximal portion of the elongated shaft. The actuating mechanism is moveable relative to the housing to move the elongated shaft along the longitudinal axis. An end effector is coupled to a distal portion of the elongated shaft. The end effector includes first and second jaw members. The first jaw member is pivotable relative to the second jaw member between an open position and a closed position. An electrically conductive tissue sealing surface is disposed on each of the jaw members and is adapted to connect to a source of electrosurgical energy. The tissue sealing surfaces are configured to conduct electrosurgical energy through grasped tissue. A tissue-dissecting electrode is disposed on a distal end of at least one of the jaw members in spaced relation to the tissue sealing surface. The at least one tissue-dissecting electrode is adapted to connect to a source of electrosurgical energy and is configured to electrosurgically dissect tissue. An insulator couples the at least one tissue-dissecting electrode to the jaw member and is configured to electrically insulate the at least one tissue-dissecting electrode from the jaw member.

Additionally or alternatively, the source of electrosurgical energy is configured to deliver a tissue-cutting electrosurgical waveform to the tissue sealing surfaces for electrosurgically cutting tissue grasped therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure and, together with the detailed description of the embodiments given below, serve to explain the principles of the disclosure.

FIG. 1 is a perspective view of an electrosurgical forceps according to an embodiment of the present disclosure including a housing, an elongated shaft, and an end effector;

FIG. 2A is an enlarged, perspective view of the end effector of FIG. 1 depicted with a pair of jaw members in an open configuration;

FIG. 2B is an enlarged, perspective view of the end effector of FIG. 1 depicted with the pair of jaw members in a closed configuration;

FIG. 3A is a perspective view of the end effector and elongated shaft of FIG. 1 with parts separated;

FIG. 3B is cross-sectional view taken along line 3B-3B of FIG. 3A showing a distal portion of the electrosurgical forceps of FIG. 1 depicting a tube guide;

FIG. 4 is a proximally-facing, perspective view of a rotation knob depicting a passageway for receiving the elongated shaft of FIG. 1;

FIG. 5 is a cross-sectional, perspective view of the end effector of FIG. 1;

FIG. 6 is a partial, proximal-facing perspective view of a distal portion of a jaw actuation mechanism of the end effector of FIG. 1;

FIG. 7 is a partial, distal-facing perspective view of distal portion of a knife actuation mechanism of the end effector of FIG. 1;

FIG. 8A is a perspective view of a lower jaw member of the end effector of FIG. 1;

FIG. 8B is a perspective view of a tissue sealing plate and a tissue-dissecting electrode of the lower jaw member of FIG. 8A;

FIG. 9 is a cross-sectional, perspective view of the lower jaw member of FIG. 8;

FIG. 10 is a perspective view of a proximal portion of the instrument of FIG. 1 with a portion of the housing removed revealing internal components;

FIG. 11 is a partial, side view of a proximal portion of the instrument of FIG. 1;

FIG. 12A is a perspective view of a proximal portion of the knife actuation mechanism of the end effector of FIG. 1;

FIG. 12B is a cross-sectional, side view of a knife collar of the knife actuation mechanism of the end effector of FIG. 1;

FIG. 13A is a side view of the proximal portion of the instrument of FIG. 10 depicting a movable handle in a separated position with respect to a stationary handle, which corresponds to the open configuration of the end effector depicted in FIG. 2A, and a knife trigger in a separated configuration with respect to the stationary handle, which corresponds to an un-actuated or proximal configuration of a knife with respect to the jaw members;

FIG. 13B is a side view of the proximal portion of the instrument of FIG. 10 depicting the movable handle in an intermediate position with respect to the stationary handle, which corresponds to a first closed configuration of the end effector wherein the jaw members encounter one another;

FIG. 13C is a side view of the proximal portion of the instrument of FIG. 10 depicting the movable handle in an approximated configuration with respect to the stationary handle, which corresponds to a second closed configuration of the end effector wherein the jaw members apply an appropriate pressure to generate a tissue seal; and

FIG. 13D is a side view of the proximal portion of the instrument of FIG. 10 depicting the knife trigger in an actuated configuration, which corresponds to an actuated or distal position of the knife with respect to the jaw members.

DETAILED DESCRIPTION

Referring initially to FIG. 1, an electrosurgical forceps 100 generally includes a housing 112 that supports various actuators thereon for remotely controlling an end effector 114 through an elongated shaft 116. Although this configuration is typically associated with instruments for use in laparoscopic or endoscopic surgical procedures, various aspects of the present disclosure may be practiced with traditional open instruments and in connection with endoluminal procedures as well. The housing 112 is constructed of a left housing half 112 a and a right housing half 112 b. The left and right designation of the housing halves 112 a, 112 b refer to the respective directions as perceived by an operator using the forceps 100. The housing halves 112 a, 112 b may be constructed of sturdy plastic, and may be joined to one another by adhesives, ultrasonic welding or other suitable assembly methods.

To mechanically control the end effector 114, the housing 112 supports a stationary handle 120, a movable handle 122, a trigger 126 and a rotation knob 128. The movable handle 122 is operable to move the end effector 114 between an open configuration (FIG. 2A) wherein a pair of opposed jaw members 130, 132 are disposed in spaced relation relative to one another, and a closed configuration (FIG. 2B) wherein the jaw members 130, 132 are approximated. Approximation of the movable handle 122 with the stationary handle 120 serves to move the end effector 114 to the closed configuration and separation of the movable handle 122 from the stationary handle 120 serves to move the end effector 114 to the open configuration. The trigger 126 is operable to extend and retract a knife blade 156 (see FIGS. 2A and 2B) through the end effector 114 when the end effector 114 is in the closed configuration. The rotation knob 128 serves to rotate the elongated shaft 116 and the end effector 114 about a longitudinal axis A-A extending through the forceps 114.

To electrically control the end effector 114, the stationary handle 120 supports a depressible button 137 thereon, which is operable by the user to initiate and terminate the delivery of electrosurgical energy (e.g., RF energy) to the end effector 114. The depressible button 137 is mechanically coupled to a switch 136 (FIGS. 13A-13D) disposed within the stationary handle 120 and is engageable by a button activation post 138 extending from a proximal side of the moveable handle 122 upon proximal movement of the moveable handle 122 to an actuated or proximal position (FIG. 13C). The switch 136 is in electrical communication with an electrosurgical generator 141 via suitable electrical wiring (not explicitly referenced) extending from the housing 112 through a cable 143 extending between the housing 112 and the electrosurgical generator 141. The switch 136 may be any suitable switch capable of electrically coupling the generator 141 to the end effector 114. The generator 141 may include devices such as the LigaSure® Vessel Sealing Generator and the ForceTriad® Generator sold by Covidien. The cable 143 may include a connector (not shown) thereon such that the forceps 100 may be selectively coupled electrically to the generator 141.

The upper and lower jaw members 130, 132 are electrically coupled to cable 143, and thus to the generator 141 (e.g., via respective suitable electrical wiring extending through the elongated shaft 116) to provide an electrical pathway to a pair of electrically conductive, tissue-engaging sealing plates 148, 150 disposed on the lower and upper jaw members 132, 130, respectively, and a tissue-dissecting electrode 149 disposed on lower jaw member 132. The sealing plate 148 of the lower jaw member 132 opposes the sealing plate 150 of the upper jaw member 130 and the tissue-dissecting electrode 149 extends distally from a distal-most end of jaw member 132. In some embodiments, the sealing plates 148 and 150 are electrically coupled to opposite terminals, e.g., positive or active (+) and negative or return (−) terminals associated with the generator 141. Thus, bipolar energy may be provided through the sealing plates 148 and 150 to tissue. Alternatively, the sealing plates 148 and 150 may be configured to deliver monopolar energy to tissue. In a monopolar configuration, one or both sealing plates 148 and 150 deliver electrosurgical energy from an active terminal, e.g., (+), while a return pad (not shown) is placed generally on a patient and provides a return path to the opposite terminal, e.g., (−), of the generator 141.

Each jaw member 130, 132 includes a jaw insert 140 (FIG. 9) and an insulator 142 that serves to electrically insulate the sealing plates 150, 148 from the jaw insert 140 of the jaw members 130, 132, respectively. Jaw member 132 includes an insulator 146 that serves to electrically insulate tissue-dissecting electrode 149 from sealing plate 148 and jaw insert 140 (FIG. 9). Insulator 146 also serves to space tissue-dissecting electrode 149 from sealing plate 148.

In some embodiments, tissue-dissecting electrode 149 and sealing plate 148 are electrically coupled to opposite terminals, e.g., positive or active (+) and negative or return (−) terminals associated with the generator 141 such that bipolar energy is delivered to tissue-dissecting electrode 149 and sealing plate 148 to generate an energy potential therebetween for dissecting tissue contacted by tissue-dissecting electrode 149 and/or sealing plate 148 with bipolar electrosurgical energy. In this manner, an energy potential may be generated between tissue-dissecting electrode 149 and either sealing plate 148 or sealing plate 150 or both sealing plates 148, 150. That is, both sealing plates 148, 150 may be energized together or separately, with the same or different polarity (e.g., (+) or (−)), or any combination thereof. As a practical example, during a tissue dissecting procedure, sealing plates 148, 150 may both be energized with the same polarity (e.g., (+)) and tissue-dissecting electrode 149 may be energized with the opposite polarity (e.g., (−)) to generate an energy potential between tissue-dissecting electrode 149 and one or both of sealing plates 148, 150 (e.g., one of the sealing plates may be electrically deactivated during tissue dissection) such that tissue-dissecting electrode 149 may be utilized to dissect tissue using bipolar electrosurgical energy. Alternatively, tissue-dissecting electrode 149 may be configured to deliver monopolar energy to tissue. In a monopolar configuration, tissue-dissecting electrode 149 delivers electrosurgical energy from an active terminal, e.g., (+), while a return pad (not shown) is placed generally on a patient and provides a return path to the opposite terminal, e.g., (−), of the generator 141.

Electrosurgical energy may be delivered to tissue through the sealing plates 148, 150 to effect a tissue seal. During tissue sealing, tissue-dissecting electrode 149 may be electrically deactivated. Once a tissue seal is established, a knife blade 156 having a sharpened distal edge 157 may be advanced through a knife channel 158 defined in one or both jaw members 130, 132 to transect the sealed tissue. Although the knife blade 156 is depicted in FIG. 2A as extending from the elongated shaft 116 when the end effector 114 is in an open configuration, in some embodiments, extension of the knife blade 156 into the knife channel 158 when the end effector 114 is in the open configuration is prevented, as discussed below with reference to FIGS. 13A-13D. In some embodiments, sealing plates 148, 150 may conduct electrosurgical energy through tissue grasped therebetween to electrosurgically cut tissue. With this purpose in mind, the generator 141 is configured to generate various electrosurgical waveforms suitable for use in performing various electrosurgical procedures (e.g., tissue cutting, tissue sealing, tissue coagulation, etc.). In use, for example, the generator 141 may provide a “tissue sealing” electrosurgical waveform to sealing plates 148, 150 for sealing tissue grasped therebetween and subsequently provide a “tissue cutting” electrosurgical waveform to sealing plates 148, 150 for electrosurgically cutting the sealed tissue grasped therebetween.

Referring now to FIGS. 2A-3A, the end effector 114 may be moved from the open configuration (FIG. 2A) wherein tissue (not shown) is received between the jaw members 130, 132, and the closed configuration (FIG. 2B), wherein the tissue is clamped and treated. The jaw members 130, 132 pivot about a pivot pin 144 to move the end effector 114 to the closed configuration of FIG. 2B wherein the sealing plates 148, 150 provide a pressure to tissue grasped therebetween. In some embodiments, to provide an effective tissue seal, a pressure within a range between about 3 kg/cm² to about 16 kg/cm² and, desirably, within a working range of about 7 kg/cm² to about 13 kg/cm², may be applied to the tissue. Also, in the closed configuration, a separation or gap distance is maintained between the sealing plates 148, 150 by an array of stop members 154 (FIG. 2A) disposed on or adjacent the sealing plates 148, 150. The stop members 154 contact opposing surfaces on the opposing jaw member 130, 132 and prohibit further approximation of the sealing plates 148, 150. In some embodiments, to provide an effective tissue seal, an appropriate gap distance of about 0.001 inches to about 0.010 inches and, desirably, between about 0.002 inches to about 0.005 inches, may be provided. In some embodiments, the stop members 154 are constructed of a heat-resistant ceramic deposited onto the jaw members 130, 132. In other embodiments, the stop members 154 are constructed of an electrically non-conductive plastic molded onto the jaw members 130, 132, e.g., by a process such as overmolding or injection molding.

Referring to FIG. 3A, the elongated shaft 116 includes various longitudinal components that operatively couple the end effector 114 to the various actuators supported by the housing 112 (FIG. 1). An outer shaft member 160 defines an exterior surface of the elongated shaft 116 and houses other components therein as described below. The outer shaft member 160 is configured for longitudinal motion with respect to an inner actuation member 180 axially received within the outer shaft member 160. The inner actuation member 180 may be a rod, a shaft, a tube, folded metal, stamped metal, or other suitable structure. A proximal portion 166 of the outer shaft member 160 is configured for receipt within the housing 112 (FIG. 1), and includes features for operatively coupling the outer shaft member 160 to various elements of the housing 112. More specifically, the proximal portion 166 of the outer shaft member 160 includes, in order from distal to proximal, a longitudinal slot 169 to couple the outer shaft member 160 to the rotation knob 128, a longitudinal knife slot 168 defined therethrough, a pair of opposing distal locking slots 161 a, 161 b, and a pair of opposing proximal locking slots 171 a, 171 b. The connection established between the outer shaft member 160 and the rotation knob 128 is described below with reference to FIG. 4.

A distal portion 186 of the inner actuation member 180 includes a longitudinal recess 190 defined therein that provides clearance for the pivot pin 144 and thus, permits longitudinal reciprocation of the pivot pin 144 (via longitudinal reciprocation of the outer shaft member 160) independent of the inner actuation member 180. Distal to the longitudinal recess 190, a cam pin 192 is mechanically coupled (e.g., via welding, friction-fit, laser welding, etc.) to the distal portion 186 of the inner actuation member 180. A proximal portion 188 of the inner actuation member 180 includes a washer 187 coupled thereto (FIG. 10). The washer 187 is captured within the housing 112 and serves to prohibit longitudinal motion of the inner actuation member 180 parallel to the longitudinal axis A-A.

The pivot pin 144 extends through a proximal portion of each of the jaw members 130, 132 to pivotally support the jaw members 130, 132 at the distal end of the inner actuation member 180. A proximal portion of each of the jaw members 130, 132 includes two laterally spaced parallel flanges or “flags” 130 a, 130 b and 132 a, 132 b respectively, extending proximally from a distal portion of the jaw members 130 and 132 (FIGS. 3A, 5, and 7-9). A lateral cam slot 130 c and a lateral pivot bore 130 d extend through each of the flags 130 a, 130 b of the upper jaw member 130 (FIG. 3A). Similarly, a lateral cam slot 132 c and a lateral pivot bore 132 d extend through each of the flags 132 a, 132 b of the lower jaw member 132 (FIGS. 8 and 9). The pivot bores 130 d, 132 d receive the pivot pin 144 in a slip-fit relation that permits the jaw members 130, 132 to pivot about the pivot pin 144 to move the end effector 114 between the open and closed configurations (FIGS. 2A and 2B, respectively).

A knife rod 102 is coupled (e.g., via welding) at a distal-most end to the sharpened knife blade 156 and includes an angled proximal end 108 that provides a mechanism for operatively coupling the knife rod 102 to the trigger 126. In some embodiments, the angled proximal end 108 of the knife rod 102 is formed by bending the knife rod 102 ninety degrees at its proximal end during manufacturing. The connection between the knife rod 102 and the trigger 126 is described in detail below with reference to FIGS. 10, 11, 12A, and 12B. The sharpened distal edge 157 of the knife blade 156 may be applied to the distal end of the knife blade 156 using a variety of manufacturing techniques such as, for example, grinding, coining, electrochemical etching, electropolishing, or other suitable manufacturing technique, for forming sharpened edges.

Referring to FIGS. 3A and 3B, a tube guide 109 is disposed within the outer shaft member 160 and includes a lumen 107 axially disposed therethrough. The inner actuation member 180 is received within the guide lumen 107, which serves to orient and align the inner actuation member 180 within the outer shaft member 160. The knife rod 102 is received within a longitudinal guide recess 105 formed in the outer surface of the guide tube 109. The guide recess 105 serves to guide longitudinal motion of the knife rod 102 within the outer shaft member 160 and to radially space the knife rod 102 from the inner actuation member 180 to prevent the inner actuation member 180 from interfering with reciprocal motion of the knife rod 102. The tube guide 109 may include one or more suitable lumens axially disposed therethrough that serve to receive electrical wiring (not shown) configured to electrically connect sealing plates 148, 150 and tissue-dissecting electrode 149 to the generator 141 through cable 143.

Referring now to FIG. 4, the rotation knob 128 includes a distal portion 125 extending distally therefrom and a passageway 129 defined therethrough for receiving the outer shaft member 160. The passageway 129 has a generally circular profile corresponding to the circular profile of the outer shaft member 160. The passageway 129 includes a longitudinal keying member 124 that is configured to align with and be seated within longitudinal slot 169 (FIG. 3A) of the outer shaft member 160. The keying member 124 projects laterally inward along the length of passageway 129 such that the insertion of the outer shaft member 160 into the passageway 129 of the rotation knob 128 operatively couples the outer shaft member 160 to the rotation knob 128. Rotational motion imparted to the rotation knob 128 may thus impart rotational motion to each of the components of the elongated shaft 116, and to the end effector 114, which is coupled thereto. As shown in FIGS. 10, 11, and 13A-13D, the rotation knob 128 is supported in the housing 112 and, as shown in FIG. 1, extends radially outward from opposing sides of the housing 112 (only shown extending radially outward from housing half 112 b).

Referring now to FIG. 5, the end effector 114 is coupled to the distal end of the inner actuation member 180 by the cam pin 192. The cam pin 192 represents a longitudinally stationary reference for longitudinal movement of the outer shaft member 160 and the knife rod 102. The cam pin 192 extends through the flags 132 a, 132 b of the lower jaw member 132 and the flags 130 a and 130 b of the upper jaw member 130.

Referring now to FIG. 6, the end effector 114 is shown in the open configuration. Since the inner actuation member 180 is coupled to the cam pin 192, when the outer shaft member 160 (removed from view in FIG. 6 for clarity) is in an unactuated or distal position such that the inner actuation member 180 is in a proximal position relative to the outer shaft member 160, the cam pin 192 is located in a proximal position in cam slots 130 c and 132 c defined through the flags 130 a, 130 b, 132 a, 132 b of the jaw members 130, 132, respectively.

The outer shaft member 160 may be drawn proximally relative to the inner actuation member 180 and the cam pin 192 to move the end effector 114 to the closed configuration (see FIG. 2B). Since the longitudinal position of the cam pin 192 is fixed, and since the cam slot 130 c is obliquely arranged with respect to the longitudinal axis A-A, proximal retraction of the outer shaft member 160 induces distal translation of the cam pin 192 through the cam slots 130 c, 132 c such that the jaw member 130 pivots toward jaw member 132 about the pivot pin 144. Conversely, when the end effector 114 is in the closed configuration, longitudinal translation of the outer shaft member 160 in a distal direction induces proximal translation of the cam pin 192 through the cam slots 130 c, 132 c such that jaw member 130 pivots away from jaw member 132 toward the open configuration.

In some embodiments, the inner actuation member 180 may be configured to move relative to the outer shaft member 160 to move the end effector 114 between the open and closed configurations. In this scenario, the moveable handle 122 may be operably coupled to the inner actuation member 180 and the washer 187 coupled to the proximal portion 188 of the inner actuation member 180 may be removed such that the inner shaft member 180 is free to move longitudinally along the longitudinal axis A-A upon actuation of the moveable handle 122. Proximal retraction of the inner actuation member 180 may induce proximal translation of the cam pin 192 through the cam slots 130 c, 132 c such that the jaw member 130 pivots away from jaw member 132 about the pivot pin 144 toward the open configuration. Conversely, when the end effector 114 is in the open configuration, longitudinal translation of the inner actuation member 180 in a distal direction induces distal translation of the cam pin 192 through the cam slots 130 c, 132 c such that jaw member 130 pivots toward jaw member 132 toward the closed configuration.

Referring now to FIG. 7, the pins 144, 192 do not interfere with the reciprocal motion of the knife blade 156. A proximal portion of the insulator 142 forms a blade guide 152 (also see FIGS. 5, 8, and 9) that serves to align the knife blade 156 such that the knife blade 156 readily enters the knife channel 158 defined in the jaw members 130, 132 (jaw member 130 removed from view in FIG. 7 for clarity).

Referring now to FIGS. 8A, 8B, and 9, the lower jaw member 132 is constructed of a jaw insert 140, insulators 142, 146, a sealing plate 148, and a tissue-dissecting electrode 149. The flags 132 a, 132 b of the jaw member 132 define a proximal portion of the jaw insert 140 and a generally u-shaped profile of the jaw insert 140 extends distally to support the tissue engaging portion of the jaw member 132. Upper jaw member 130 includes a sealing plate 150, a jaw insert 140, and an insulator 142.

The insulator 142 of jaw members 130, 132 as well as the insulator 146 of jaw member 132 may be constructed of an electrically insulative plastic such as a polyphthalamide (PPA) (e.g., Amodel®), polycarbonate (PC), acrylonitrile butadiene styrene (ABS), a blend of PC and ABS, nylon, ceramic, silicone, etc. As shown in FIG. 8B, an underside of a distal end of sealing plate 148 is formed to at least partially surround the insulator 146 to secure the insulator 146 to the underside of sealing plate 148. Insulator 146 is, in turn, secured to tissue-dissecting electrode 149 (e.g., via adhesive, overmolding, etc.) to couple tissue-dissecting electrode 149 to jaw member 132 while maintaining tissue-dissecting electrode 149 in spaced relation with sealing plate 148. Additionally or alternatively, insulator 146 may be secured to the underside of sealing plate 148 via any suitable method including, without limitation, adhesive or overmolding. In some embodiments, insulator 146 may be formed of silicone or a silicone-based material that has a high melting temperature. Once tissue-dissecting electrode 149 is secured to jaw member 132 via insulator 146, the insulator 142 may be overmolded onto the jaw insert 140 in either a single-shot or a two-shot injection molding process to at least partially encapsulate insulator 146 and to couple sealing plate 148 to jaw member 132 in spaced relation with its jaw insert 140, as depicted in FIG. 9. Substantially as described above with respect to sealing plate 148, the insulator 142 may be overmolded onto the jaw insert 140 of jaw member 130 in either a single-shot or a two-shot injection molding process such that sealing plate 150 is coupled to jaw member 130 and in spaced relation with its jaw insert 140. Additionally or alternatively, the insulator 142 may be mechanically coupled to the jaw insert 140, e.g., pressed, snapped, glued, etc. Various features may be molded into the insulator 142 that facilitate the attachment of the sealing plates 148, 150 to the jaw inserts 140. For example, tabs may be provided that permit a snap-fit attachment, or ridges may be formed that permit ultrasonic welding of the sealing plates 148, 150 onto the insulators 142. In some embodiments, the insulator 142 on the lower jaw member 132 forms a tissue stop 142 a extending therefrom adjacent to the knife channel 158 and proximal to the sealing plate 148. The tissue stop 142 a serves to prevent tissue from entering the distal end of the outer shaft member 160 and to prevent splay of the flags 130 a, 130 b of the upper jaw member 130. In some embodiments, the tissue stop 142 a may be formed by the insulator 142 on the upper jaw member 130 or on both the upper jaw member 130 and the lower jaw member 132. The tissue stop 142 a may also serve to align the knife blade 156 as the knife blade 156 enters the knife channel 158 defined in the jaw members 130, 132.

Referring now to FIG. 8B, in some embodiments, an underside of sealing plate 148 includes a flex circuit 147 disposed thereon. Flex circuit 147 extends between a proximal portion of sealing plate 148 and tissue-dissecting electrode 149 to electrically connect tissue-dissecting electrode 149 to suitable electrical wiring (not shown) that, in turn, serves to electrically connect tissue-dissecting electrode 149 to generator 141. Flex circuit 147 may be encapsulated by a protective material such as, for example, polyimide, and secured to the underside of sealing plate 148 prior to the overmolding of insulator 142 onto the jaw insert 140 of jaw member 132. In this scenario, flex circuit 147 and sealing plate 148 may be electrically connected to separate electrical wires (not shown) that, in turn, electrically connect flex circuit 147 and sealing plate 148 to separate terminals, e.g., positive or active (+) and negative or return (−) terminals associated with the generator 141.

Referring now to FIG. 10, the connection of the movable handle 122 and the knife trigger 126 to the longitudinally movable components of the elongated shaft 116 is described. The movable handle 122 may be manipulated to impart longitudinal motion to the outer shaft member 160, and the knife trigger 126 may be manipulated to impart longitudinal motion to the knife rod 102. As discussed above, longitudinal motion of the outer shaft member 160 serves to move the end effector 114 between the open configuration of FIG. 2A and the closed configuration of FIG. 2B, and longitudinal motion of the knife rod 102 serves to move knife blade 156 through knife channel 158 (FIG. 2A).

The movable handle 122 is operatively coupled to the outer shaft member 160 by a clevis 178 defined at an upper end of the movable handle 122. The clevis 178 is pivotally supported on the housing 112. The clevis 178 extends upwardly about opposing sides of a drive collar 184 (FIG. 11) supported on the outer shaft member 160 and includes rounded drive surfaces 197 a and 197 b thereon. Drive surface 197 a engages a proximal-facing surface of a distal spring washer 184 a and drive surface 197 b engages a distal facing surface of a proximal rim 184 b of the drive collar 184 (FIG. 11). The distal spring washer 184 a engages a proximal facing surface of a distal spring stop 184 c that, in turn, engages the opposing distal locking slots 161 a, 161 b (FIG. 3A) extending through the proximal portion 166 (FIG. 3A) of the outer shaft member 160 to couple the distal spring stop 184 c to the outer shaft member 160. The drive surfaces 197 a, 197 b are arranged along the longitudinal axis A-A such that pivotal motion of the movable handle 122 induces corresponding longitudinal motion of the drive collar 184 (FIG. 11) along the longitudinal axis A-A.

Referring now to FIG. 11, proximal longitudinal motion may be imparted to the outer shaft member 160 by pushing the proximal rim 184 b of the drive collar 184 proximally with the movable handle 122 (FIG. 10) as indicated by arrow D4 (FIG. 11). A spring 189 is constrained between a proximal facing surface of the drive collar 184 and a proximal spring stop 115. The proximal spring stop 115 engages the opposing proximal locking slots 171 a, 171 b (FIG. 3A) extending through the proximal portion 166 (FIG. 3A) of the outer shaft member 160 to couple the proximal spring stop 115 to the outer shaft member 160. Thus, the proximal spring stop 115 serves as a proximal stop against which spring 189 compresses.

Distal longitudinal motion is imparted to the outer shaft member 160 by driving the drive collar 184 distally with the movable handle 122. Distal longitudinal motion of the drive collar 184 induces a corresponding distal motion of the outer shaft member 160 by virtue of the coupling of the drive collar 184 to opposing distal locking slots 181 a, 181 b extending through the proximal portion 166 of the outer shaft member 160 (FIG. 3A).

Proximal longitudinal motion of the outer shaft member 160 draws jaw member 132 proximally such that the cam pin 192 advances distally to pivot jaw member 130 toward jaw member 132 to move the end effector 114 to the closed configuration as described above with reference to FIG. 6. Once the jaw members 130 and 132 are closed, the outer shaft member 160 essentially bottoms out (i.e., further proximal movement of the outer shaft member 160 is prohibited since the jaw members 130, 132 contact one another). Further proximal movement of the movable handle 122 (FIG. 10), however, will continue to move the drive collar 184 proximally. This continued proximal movement of the drive collar 184 further compresses the spring 189 to impart additional force to the outer shaft member 160, which results in additional closure force applied to tissue grasped between the jaw members 130, 132 (see FIG. 2B).

Referring again to FIG. 10, the trigger 126 is pivotally supported in the housing 112 about a pivot boss 103 protruding from the trigger 126. The trigger 126 is operatively coupled to the knife rod 102 by a knife connection mechanism 104 such that pivotal motion of the trigger 126 induces longitudinal motion of the knife rod 102. The knife connection mechanism 104 includes upper flanges 126 a, 126 b of the trigger 126 and a knife collar 110.

Referring now to FIGS. 11, 12A, and 12B, the knife collar 110 includes a pair of integrally formed pin bosses 139 a, 139 b extending from opposing sides thereof. As shown by FIG. 12B, the knife collar 110 includes an interior circular channel 113 that captures the angled proximal end 108 of the knife rod 102 to couple the knife rod 102 to the knife collar 110. Upon longitudinal motion of the outer shaft member 160, the angled proximal end 108 of the knife rod 102 translates longitudinally within knife slot 168 (FIG. 3A) of the outer shaft member 160 such that the longitudinal motion of outer shaft member 160 is unimpeded by the angled proximal end 108 of the knife rod 102. Upon rotation of the elongated shaft 116 and end effector 114 about the longitudinal axis A-A via the rotation knob 128 (FIG. 1), the angled proximal end 108 of the knife rod 102 freely rotates within the interior circular channel 113 of the knife collar 110 such that the outer and inner actuation members 160 and 180 (removed from view in FIG. 12B for clarity), and the knife rod 102 rotate within the knife collar 110 about the longitudinal axis A-A. In this way, the knife collar 110 serves as a stationary reference for the rotational movement of the outer shaft member 160, the inner actuation member 180, and the knife rod 102.

Referring again to FIG. 10, the upper flanges 126 a, 126 b of the trigger 126 include respective slots 127 a, 127 b defined therethrough that are configured to receive the pin bosses 139 a, 139 b, respectively, of the knife collar 110 such that pivotal motion of the trigger 126 induces longitudinal motion of the knife collar 110 and, thus, the knife rod 102 by virtue of the coupling of knife rod 102 to the knife collar 110.

Referring now to FIGS. 11 and 12A, when the trigger 126 is moved to induce motion of the knife collar 110 in order to translate the blade 156 through the knife channel 158, the knife collar 110 translates along the outer shaft member 160 in the direction of arrow A5 to abut a spring 119 such that spring 119 compresses against the distal portion 125 of the rotation knob 128 (FIG. 12A). The spring 119 biases the knife collar 110 proximally along the outer shaft member 160.

Referring now to FIGS. 13A, 13B, 13C and 13D, a sequence of motions may be initiated by moving the movable handle 122 to induce motion of the outer shaft member 160 in order to close the jaws 130, 132, and by moving the trigger 126 to induce motion of the knife collar 110 in order to translate the blade 156 through the knife channel 158. Initially, both the moveable handle 122 and the knife trigger 126 are in a distal or un-actuated position as depicted in FIG. 13A. This arrangement of the moveable handle 122 and trigger 126 sustains the end effector 114 in the open configuration (FIG. 2A) wherein the jaw members 130, 132 are substantially spaced from one another, and the knife blade 156 is in a retracted or proximal position with respect to the jaw members 130, 132. When both the moveable handle 122 and the knife trigger 126 are in the distal, un-actuated position, pivotal motion of the knife trigger 126 in a proximal direction, i.e., toward the stationary handle 120, is passively prohibited by interference between the trigger 126 and moveable handle 122. This interference prohibits advancement of the knife blade 156 through the knife channel 158 when the end effector 114 is in the open configuration.

The movable handle 122 may be moved from the distal position of FIG. 13A to the intermediate position depicted in FIG. 13B to move the jaw members 130, 132 to the closed configuration (FIG. 2B). As the movable handle 122 pivots in the direction of arrow M1 (FIG. 13B), the drive surface 197 b of the movable handle 122 engages the proximal rim 184 b of the drive collar 184. The drive collar 184 is driven proximally such that the spring 189 biases the proximal spring stop 115 and, thus, the outer shaft member 160 is driven proximally in the direction of arrow M2 (FIG. 13B). As discussed above with reference to FIG. 6, proximal movement of the outer shaft member 160 serves to translate the cam pin 192 distally though the cam slots 130 c, 132 c (FIG. 3A) of the jaw members 130, 132, respectively, and thus pivot jaw member 130 toward jaw member 132 (FIG. 2B). As the jaw members 130, 132 engage one another and no further pivotal movement of the jaw members 130, 132 may be achieved, further distal movement of the cam pin 192 and further proximal movement of the outer shaft member 160 are prevented.

As the movable handle 122 is moved from the distal position of FIG. 13A to the intermediate position depicted in FIG. 13B, a tooth 122 a extending proximally from an upper portion of the moveable handle 122 engages a clicker tab 120 a supported within the stationary handle 120 to generate a tactile and/or an audible response. The clicker tab 120 a may be constructed of a plastic film, sheet metal, or any suitable material configured to generate a “clicking” sound as the clicker tab 120 a is engaged and disengaged by the tooth 122 a. This response generated by the clicker tab 120 a corresponds to a complete grasping of tissue between the jaw members 130, 132 and serves to indicate to the surgeon that further pivotal motion of the moveable handle 122 in a proximal direction, i.e., toward the stationary handle 120, will cause the button activation post 138 to engage the depressible button 137. As the moveable handle 122 is moved from the intermediate position of FIG. 13B to the actuated or proximal position of FIG. 13C, the button activation post 138 depresses the depressible button 137, thereby activating the switch 136 disposed within the stationary handle 120 to initiate the delivery of electrosurgical energy to the end effector 114 to generate a tissue seal.

As the movable handle 122 is moved from the intermediate position of FIG. 13B to the actuated or proximal position of FIG. 13C, the pressure applied by the jaw members 130, 132 is increased. As the movable handle 122 pivots further in the direction of arrow M3 (FIG. 13C), the drive surface 197 b presses the proximal rim 184 b of the drive collar 184 further proximally against the spring 189 in the direction of arrow M4 (FIG. 13C). The spring 189 is compressed against the proximal spring stop 115, and a tensile force is transmitted through the outer shaft member 160 to the jaw members 130, 132. The tensile force supplied by the spring 189 ensures that the jaw members 130, 132 apply an appropriate pressure to effect a tissue seal.

When the movable handle 122 is in the actuated or proximal position, the knife trigger 126 may be selectively moved from the distal position of FIG. 13C to the proximal position of FIG. 13D to advance the knife blade 156 distally through knife channel 158. The knife trigger 126 may be pivoted in the direction of arrow M5 (FIG. 13D), about pivot boss 103 to advance the flanges 126 a, 126 b of the knife trigger 126 distally in the direction of arrow M6 such that the pin bosses 139 a, 139 b translate within respective slots 127 a, 127 b from the position shown in FIGS. 13A-13C to the position shown in FIG. 13D (flange 126 b, pin boss 139 b, and slot 127 b are obstructed from view in FIGS. 13A-13D). Movement of flanges 126 a, 126 b draws the knife collar 110 distally, which induces distal longitudinal motion of the knife rod 102 by virtue of the coupling of the knife rod 102 to the knife collar 110, as described above with reference to FIG. 12B.

The various embodiments disclosed herein may also be configured to work with robotic surgical systems and what is commonly referred to as “Telesurgery”. Such systems employ various robotic elements to assist the surgeon in the operating theatre and allow remote operation (or partial remote operation) of surgical instrumentation. Various robotic arms, gears, cams, pulleys, electric and mechanical motors, etc. may be employed for this purpose and may be designed with a robotic surgical system to assist the surgeon during the course of an operation or treatment. Such robotic systems may include, remotely steerable systems, automatically flexible surgical systems, remotely flexible surgical systems, remotely articulating surgical systems, wireless surgical systems, modular or selectively configurable remotely operated surgical systems, etc.

The robotic surgical systems may be employed with one or more consoles that are next to the operating theater or located in a remote location. In this instance, one team of surgeons or nurses may prep the patient for surgery and configure the robotic surgical system with one or more of the instruments disclosed herein while another surgeon (or group of surgeons) remotely control the instruments via the robotic surgical system. As can be appreciated, a highly skilled surgeon may perform multiple operations in multiple locations without leaving his/her remote console which can be both economically advantageous and a benefit to the patient or a series of patients.

The robotic arms of the surgical system are typically coupled to a pair of master handles by a controller. The handles can be moved by the surgeon to produce a corresponding movement of the working ends of any type of surgical instrument (e.g., end effectors, graspers, knifes, scissors, etc.) which may complement the use of one or more of the embodiments described herein. The movement of the master handles may be scaled so that the working ends have a corresponding movement that is different, smaller or larger, than the movement performed by the operating hands of the surgeon. The scale factor or gearing ratio may be adjustable so that the operator can control the resolution of the working ends of the surgical instrument(s).

The master handles may include various sensors to provide feedback to the surgeon relating to various tissue parameters or conditions, e.g., tissue resistance due to manipulation, cutting or otherwise treating, pressure by the instrument onto the tissue, tissue temperature, tissue impedance, etc. As can be appreciated, such sensors provide the surgeon with enhanced tactile feedback simulating actual operating conditions. The master handles may also include a variety of different actuators for delicate tissue manipulation or treatment further enhancing the surgeon's ability to mimic actual operating conditions.

While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as examples of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Although the foregoing disclosure has been described in some detail by way of illustration and example, for purposes of clarity or understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims. 

What is claimed is:
 1. An electrosurgical instrument, comprising: a housing; an elongated shaft extending distally from the housing, the elongated shaft defining a longitudinal axis; a movable handle operably coupled to a proximal portion of the elongated shaft and moveable relative to the housing to move the elongated shaft along the longitudinal axis; an end effector coupled to a distal portion of the elongated shaft, the end effector including first and second jaw members, the first jaw member pivotable relative to the second jaw member between an open position and a closed position; an inner shaft axially disposed within the elongated shaft and having a distal portion coupled to at least one of the first or second jaw members and a proximal portion disposed within the housing, wherein movement of the elongated shaft along the longitudinal axis and relative to the inner shaft moves the first jaw member between the open and closed positions; an electrically conductive tissue sealing surface disposed on each of the jaw members and adapted to connect to a source of electrosurgical energy, the tissue sealing surfaces configured to conduct electrosurgical energy through tissue grasped therebetween; a tissue-dissecting electrode disposed on a distal end of at least one of the jaw members in spaced relation to the tissue sealing surface, the tissue-dissecting electrode adapted to connect to a source of electrosurgical energy and configured to operate in a first mode, wherein the at least one tissue-dissecting electrode and at least one of the tissue sealing surfaces generates a bipolar energy potential therebetween for electrosurgically dissecting tissue, and a second mode, wherein the at least one tissue-dissecting electrode is configured to couple to a return pad to generate a monopolar energy potential therebetween to electrosurgically dissect tissue; and an insulator coupling the at least one tissue-dissecting electrode to the jaw member and configured to electrically insulate the at least one tissue-dissecting electrode from the jaw member.
 2. The electrosurgical instrument according to claim 1, wherein the at least one tissue-dissecting electrode extends distally from a distal end of the at least one jaw member.
 3. The electrosurgical instrument according to claim 1, wherein the at least one tissue-dissecting electrode is configured to dissect tissue when the first jaw member is in the open position.
 4. The electrosurgical instrument according to claim 1, wherein the at least one tissue-dissecting electrode is configured to dissect tissue when the first jaw member is in the closed position.
 5. The electrosurgical instrument according to claim 1, wherein at least one of the tissue sealing surfaces includes a flex circuit disposed thereon configured to electrically connect the at least one tissue-dissecting electrode to a source of electrosurgical energy.
 6. The electrosurgical instrument according to claim 1, wherein during the first mode, the at least one tissue-dissecting electrode is configured to be energized with a first polarity of electrosurgical energy and at least one of the tissue sealing surfaces is configured to be energized with a second polarity of electrosurgical energy.
 7. The electrosurgical instrument according to claim 1, wherein the at least one tissue-dissecting electrode is electrically deactivated during sealing of tissue grasped between the tissue sealing surfaces.
 8. The electrosurgical instrument according to claim 1, wherein the end effector is configured to electrosurgically dissect tissue contacted by the tissue-dissecting electrode and at least one of the tissue sealing surfaces.
 9. The electrosurgical instrument according to claim 1, further comprising a cam slot disposed on the second jaw member and configured to move relative to a cam pin coupled to the distal portion of the inner shaft to move the first jaw member between the open position and the closed position upon movement of the elongated shaft along the longitudinal axis and relative to the inner shaft.
 10. The electrosurgical instrument according to claim 1, further comprising a knife advanceable along the longitudinal axis through a knife channel extending at least partially through the jaw members to cut tissue grasped therebetween.
 11. The electrosurgical instrument according to claim 1, further comprising a switch supported by the housing and engageable by the movable handle to control delivery of electrosurgical energy from a source of electrosurgical energy to the end effector.
 12. The electrosurgical instrument according to claim 1, wherein the second jaw member is mechanically coupled to a distal end of the elongated shaft and the first jaw member is moveable relative to the second jaw member.
 13. The electrosurgical instrument according to claim 1, wherein during the first mode, the at least one tissue-dissecting electrode conducts a first polarity of electrosurgical energy and at least one of the tissue sealing surfaces conducts a second polarity of electrosurgical energy.
 14. The electrosurgical instrument according to claim 1, wherein the tissue sealing surfaces are configured to electrosurgically cut tissue grasped therebetween.
 15. An electrosurgical instrument, comprising: a housing; an elongated shaft extending distally from the housing, the elongated shaft defining a longitudinal axis; a movable handle operably coupled to a proximal portion of the elongated shaft and moveable relative to the housing to move the elongated shaft along the longitudinal axis; an end effector coupled to a distal portion of the elongated shaft, the end effector including first and second jaw members, the first jaw member pivotable relative to the second jaw member between an open position and a closed position; an inner shaft disposed axially within the elongated shaft and having a distal portion coupled to at least one of the first or second jaw members and a proximal portion disposed within the housing, wherein movement of the elongated shaft along the longitudinal axis and relative to the inner shaft moves the first jaw member between the open and closed positions; an electrically conductive tissue sealing surface disposed on each of the jaw members and adapted to connect to a source of electrosurgical energy, the tissue sealing surfaces configured to conduct electrosurgical energy through tissue grasped therebetween; a tissue-dissecting electrode disposed on a distal end of the second jaw member in spaced relation to the tissue sealing surface of the second jaw member, the tissue-dissecting electrode adapted to connect to a source of electrosurgical energy and configured to: electrosurgically dissect tissue during a first mode using a bipolar energy potential generated between the tissue-dissecting electrode and at least one of the tissue sealing surfaces; and electrosurgically dissect tissue during a second mode using a monopolar energy potential generated independent of the tissue sealing surfaces; and an insulator coupling the tissue-dissecting electrode to the second jaw member and configured to electrically insulate the tissue-dissecting electrode from the second jaw member.
 16. The electrosurgical instrument according to claim 15, wherein during the first mode, the tissue-dissecting electrode is configured to conduct a first polarity of electrosurgical energy and at least one of the tissue sealing surfaces is configured to conduct a second polarity of electrosurgical energy.
 17. The electrosurgical instrument according to claim 15, wherein during the first mode, the tissue-dissecting electrode is configured to conduct a first polarity of electrosurgical energy, one of the tissue sealing surfaces is configured to generate a second polarity of electrosurgical energy, and the other tissue sealing surface is configured to be electrically deactivated.
 18. The electrosurgical instrument according to claim 15, wherein the second jaw member includes a cam slot configured to receive a cam pin coupled to the distal portion of the inner shaft, the cam slot moving relative to the cam pin upon movement of the elongated shaft along the longitudinal axis and relative to the inner shaft to move the first jaw member between the open and closed positions.
 19. An electrosurgical system, comprising: a source of electrosurgical energy; a return pad operably coupled to the source of electrosurgical energy; and an electrosurgical instrument operably coupleable to the source of electrosurgical energy, the electrosurgical instrument comprising: a housing; an elongated shaft extending distally from the housing, the elongated shaft defining a longitudinal axis; a movable handle operably coupled to a proximal portion of the elongated shaft and moveable relative to the housing to move the elongated shaft along the longitudinal axis; an end effector coupled to a distal portion of the elongated shaft, the end effector including first and second jaw members, the first jaw member pivotable relative to the second jaw member between an open position and a closed position; an inner shaft disposed axially within the elongated shaft and having a distal portion coupled to at least one of the first or second jaw members and a proximal portion disposed within the housing, wherein movement of the elongated shaft along the longitudinal axis and relative to the inner shaft moves the first jaw member between the open and closed positions; an electrically conductive tissue sealing surface disposed on each of the jaw members and configured to electrically connect to the source of electrosurgical energy for conducting electrosurgical energy through tissue grasped therebetween; a tissue-dissecting electrode disposed on a distal end of at least one of the jaw members in spaced relation to the tissue sealing surface, the tissue-dissecting electrode configured to connect to the source of electrosurgical energy for electrosurgically dissecting tissue during a first mode using a bipolar energy potential generated between the tissue-dissecting electrode and at least one of the tissue sealing surfaces and during a second mode using a monopolar energy potential generated between the tissue-dissecting electrode and the return pad; and an insulator coupling the at least one tissue-dissecting electrode to the jaw member and configured to electrically insulate the at least one tissue-dissecting electrode from the jaw member.
 20. The electrosurgical system according to claim 19, wherein the source of electrosurgical energy is configured to deliver a tissue-cutting electrosurgical waveform to the tissue sealing surfaces for electrosurgically cutting tissue grasped therebetween. 